Automatic telephone-exchange system.



C. L. GOODRUM. AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPTIH, BIG- LQQLEEWYB 'Patented'Apr.3,1917.

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TINTTED @TATE@ PATENT UFFTQE.

CHARLES L. GOODRUM, OF BROOKLYN, NEW YORK, ASSIGN OR TO WESTERN ELECTRICCOMPANY, INCORPORATED, 015 NEW YORK, N. Y., A CORPORATION OF NEW YORK.

AUTOMATIC TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Apr. 3, 1917.

To all whom it may concern.

Be it known that I, CHARLES L. GoonRUM, a citizen of the United States,residing at Brooklyn, in the county of Kings and State of New York, haveinvented certain new and useful Improvements in Automatic Tele-'phone-Exchange Systems, of which the fol-v lowing is a full, clear,concise, and exact description.

This invention relates to automatic telephone exchange systems, and moreparticularly to circuit arrangements for controlling the operation of aswitch which is set in accordance with directive impulses sent out by acalling subscriber.

The object of this invention is'to provide simple and eflicient meansfor controlling the operation of a. switch in response to impulses.

A feature of this invention is a line relay having a secomlary windingin inductive r lation to its primary winding. Current set up insuch'secomlary winding controls a polarized relay to interrupt thecircuit of a stepping magnet.

A further feature of the invention is an arrangement by which the nerelay remains energized during the sending of impulses to hold open thecircuit of a release magnet.

The invention has been shown applied to a selector switch .ofthewell-known step-bystep type, and may obviously be used for controllingswitc-"es of various types.

It is thought that the invention will be best understood from thefollowing detailed description, reference being bad to the accompanyingdrawing.

in the drawingthe circuits of a selector switch are shown i full and atthe. left is shown a subscrila-i"s substation apparatus.

\Vhen the subscriber at substation 1 desires to initiate a call, heremoves his receiver from the hook, whereupon his line is extended bymeans of a; line tinder or other suitable device indicated by dottedlines at a and to the selector shown in the drawing. Linc relay 4. isthen energized over a circuit from positive pole of battery, lefthandwinding of relay l, conductor 5, sideswitch wiper (3 in its firstposition, line conductor 2, the substation apparatas of the callingsubscriber, contact springs 7 of an impulse sending device 8, lineconductor 3, side-switchwiper" U inrits first position, conduceor lO andright-hand winding of relay 4 to negative pole of batt ry. Relay 4 isenergized and remains energized until the side switch moves intoposition 3, regardless of the operation of the sender 8, this circuitbeing maintained by a shunting resistance 11, which allows sufficientcurrent to flow when contact springs 7 are separated to hold up relay 4.

When the circuit just traced was completed, an impulse was induced in asecondary winding of relay 4, this winding being 1n a clrcuit in serieswith a polarized relay 11, by means of conductors 12 and 12 Thisimpulse, however, is of such polarity as not to cause the operation ofrelay 11.

The calling subscriber now operates the sender 8 to transmit a desirednumber of impulses. At the first break of the circuit through contactsprings 7, an impulse of a polarity such as to cause the operation ofrelay l1 is'induced through the secondary winding of relay 4-. Relay l1attracts its armature and closes a circuit for the primary steppingmagnet 14, from grounded battery, winding of magnet 14 to groun at thearmature and front contact of relay 11. When the contact springs 7 againclose, an impulse is again induced in the secondary winding oi relay 4,but this time of such polarity as not to cause the operation of relay11. It will thus be seen that by the use of a polarized relay, animpulse will be transmitted to the primary stepping magnet for eachmake-aml-break oi the circuit, whereas an ordinary relay, used in placeof 90 a polarized relay. would send an impulse on each make and on eachbreak of the line circuit.

When relay 11 first attracted its armature, it completed a circuit forslow release 95 escape magnet 15, from grounded battery, winding ofmagnet 15, side-switch wiper 16 in its first position, conductor-'17,armature and front contact of relay 11 to ground. The escape magnet isenergized, and being slow to release, remains energized during thesending of the series of impulses.

After the series of impulses have been sent, the armature of relay 11remains rc tracted for a comparatively long time and escape n'iagnet 15is deiinergized, releasing the side-switch wipers controlled by it intotheir second position.

In the second position of the side switch, a circuit is closed for asecondary stepping magnet 18 from grounded battery, the wind,

ing of magnet 18, its armature and back a set of such terminals beingindicated at 23,

24 and. 25.

Assuming now that an idle condition 'of trunks is indicated by ground ontest terminals 25, and a busy conditionbythe absence of such ground, thesecondary mag; net will continue to advance the brush set until testbrush 22 encounters a terminal 25 'l \Vhen this takes having groundthereon. place, escape magnet 15 is energized over a circuit fromgrounded battery, winding of escape magnet 15, side-switch wiper 16 inits second position,brush 22 and terminal 25 to ground. The energizationof the escape magnet releases the 'side-s\vitch wipers into their thirdposition, the circuit of stepping magnet 18. The sub- ',scribers linehas now been advanced to a 1 while-the side-switch wipers are in eitherpositions, the dener-V 4 willresult in energi'zation of'a release magnet26, its circuit succeeding switch, which may be a connector or anotherselector; c v

If the subscriber desires to abandon a call their first or secondgization of line relay being from grounded battery, winding of magnet26, off-normal contact 27, sideswitch wiper28 in either first or secondposition, and armature and back contact of relay'4 to ground. Thisrelease magnet 26,

on energization completes a locking circuit for itself through itsarmature and front contact, which maintains it energized until."

the switch is fully restored, at which time this'locking' circuit isbroken by the operation of off-normal contact27.

After the side switch has moved its wipers into their third position,the release of the switch is controlled bythe succeeding switch. Therestoration of the preceding switch will put a ground on terminal 25. Acircuit is then completed for release magnet 2.6 from grounded battery,winding of magnet 26, off-normal contact 27, side-switch Wiper. 28 inits third position, brush .22 and said stepping relay,

.contact of said first rel and permanently opens 1n inductive pulses ;tosaid relay,

switch as previously described.

What is claimed is:

1. In a control circuit, a relay having .a

.primary winding and a secondary winding 1n inductive relation thereto,a polarized stepping relay in circuit with said secondary winding, astepping magnetcontrolled by a release magnet, anda circuitthereforextending through a back ay. r I

In a telephone exchange system, an automatic switch, an impulse circuittherefor,

a polarized relay, a stepping magnet controlled thereby, a circuit forsaid relay, a reay arrangedmo inductively unite said circuits, a releasemagnet, and a circuit theresaid circuit extending through a front for,contact .of said last named relay.

3. In a telephone exchange system, an incoming. line, outgoing lines, anautomatic switch for interconnecting said lines,-a relay having aprimary windin in circuit with said incoming line and a secondarywinding relation thereto, and an impulse sending device for transmittingimmeans to control the operation of said, switch by'currents induced insaid secondary winding by such impulses, said relay being maintaineden'- ergized during the-sending of impulses.

4. In a telephone exchange system, an incoming line, switch forinterconnecting said lines, controlling circuitstherefor, a controllingswitch including a plurality of Wipers and contacts, an impulse sendingdevice, having two windings in inductive outgoing lines, an automatic' arelay relation for controlling the setting of said automatic switch, andmeans including a back contact of said relay for preventing therelease.of said automatic switch in certain positions of saidcontrolling switch,

5. An automatic switch, an impulse circuit therefor, a circuitcontrolling the operation bf said switch, and means for inductivelyunitin said circuits, said means being arranged to prevent the releaseof said .switch in certain stages of its operation.

In witness whereof, I hereunto subscribe 1015 my name this 8th day ofSeptember A. D,, 1916.

CHARLES L. GOODRUM.

